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<br />EVALUATION OF SAMPLE ADEQUACY <br />' Sample adequacy was obtained for cover and production in each of the two reference areas <br />(Table 12). Adequacy calculations were not made for shrub density in the reference areas because <br />the standard for reclamation success was based on a stipulated value rather on the basis of <br />' comparison with a reference area. <br />For the two reclaimed areas, sample adequacy was obtained for cover, production and <br />shrub density in both areas. Sample adequacy for production was based on fresh weights obtained <br />in the Seld. After drying, the biomass data sets were again evaluated for adequacy. Using the dry <br />weights, the adequate sample size for production for the 1984 reclaimed area was determined to be <br />59 samples. The fresh weight data predicted that 55 samples would be adequate. <br />' EVALUATION OF REVEGETATION SUCCESS <br />' Cover and Production. The Colorado Division of Minerals and Geology Guideline <br />Regarding Selected Coal Mine Bond Release Issues (March 17, 1995) provides approaches for <br />evaluating the success of revegetation on coal mined lands. For the reclaimed areas at the Walden <br />' Coal Company Mine, the approach titled `°I'echnical Standard or Simple Reference Area <br />Comparison Weighted Sampling in Bond Release Block" was used to evaluate success for cover <br />and production With this approach, pooled weighted mean and standard error of the mean values <br />' aze obtained for combinations of reclaimed areas. To conduct this analysis, the cover and <br />production data for the 1984 and 1988 areas were pooled using the approach outlined on page 22 <br />of the guideline referenced above. Pooled values are weighted based on the areal extent of each of <br />' the reclaimed areas. For the 1984 azea at the Walden Site, the weighing factor was 29/112 <br />(0.25893) and for the 1988 area the weighting factor was 83/112 (0.74107). <br />' Weighted means for the reclaimed area were calculated as follows: <br />Mean Total Vegetation Cover = 29/112 x (32.6) + 83/112 x (30.6) = 31.1 percent <br />Mean Total Ground Cover = 29/112 x (72.2) + 83/112 x (78.4) = 76.79 percent <br />Mean Total Production = 29/112 x (23.42) + 83/112 x (84.6) = 68.76 g/m= <br />' These pooled mean values were then wmpared to values obtained from the two sampled <br />reference areas. Since two reference areas were used, pooled mean values for cover and <br />production were used to obtain the initial comparison values. The pooled mean values corrected <br />' for differences in sample size were as follows: <br />100 % Mean Total Vegetation Cover = 35.5 percent <br />100 % Mean Total Ground Cover = 83.46 percent <br />' 100 % Mean Total Production = 40.11 g/m~ <br />The actual mean values were then converted to the cover and production standards by <br />' taking 90 % of the pooled mean values: <br />90 % Mean Total Vegetation Cover = 31.95 percent <br />' 90 % Mean Total Ground Cover = 75.12 percent <br />90 % Mean Total Production = 36.1 g/m= <br />' -4- <br />